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Comment by slfnflctd | Hacker News Reader

Since I haven't seen anyone bring up the viability of this method yet, here are a few additional bits of info I dug up:

> the total mass of the completed apparatus is around 400 kg with 20 kg of alcohol in the refrigeration cycle

> The group, led by Malcolm McCulloch noted that the design was still "nowhere near commercialised", but might allow the efficiency of the original Einstein–Szilárd design to be quadrupled.

It would be great if someone could improve this tech to where there's a breakeven point of ownership (preferably less than 20 years) when it becomes a better deal than other modern refrigerators.

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> It would be great if someone could improve this tech to where there's a breakeven point of ownership (preferably less than 20 years) when it becomes a better deal than other modern refrigerators.

Given that absorption chillers have a COP of 0.7 to 1.2 vs a vapor-compression chiller with a COP of 4-6, it’s likely impossible to create an absorption chiller/refrigerator that equals or exceeds a vapor-compression chiller/refrigerator due to physics/thermodynamics. This isn’t much of a downside for absorption chillers powered by waste heat since the energy would otherwise be lost.

Someone smarter than I am will have to explain why, all I know is that vapor-compression refrigeration is 4-6x more efficient than absorption refrigeration.

Thank you, that's the sort of response I was hoping for, actually analyzing the efficiency of the thing. Waste heat is something I think we can get a lot more juice out of in the future.

I'd happily pay for a silent fridge with much less than a 20 year breakeven point.

Silent and ostensibly failure free to boot.

Reading your and others comment I wonder what sort of refrigerators and freezers you have. Mine are about 10 years old now, Bosch, full height and whatever the best energy class was available at the time.

I'm very sound sensitive but rarely do I hear any noise from them unless I recently opened them for an extended period. Do we just have quieter appliances in Scandinavia than the rest of the world or something?

My refrigerator is a Whirlpool purchased new in 1995 at Best Buy.

It is the exact model pictured: https://bids.fowlerauction.com/auctions/38959/lot/5830641-wh...

It works perfectly (except for the hum which has been there unchanged on and off as the compressor cycles for 31 years). I'm kind of used to it by now....

For lulz I checked and you can buy working models of this fridge at estate sales for $50-$110: the one pictured sold at a 2024 estate sale auction in Alabama/Tennessee/Georgia for $110.

The efficiency of most existing heat-driven refrigerator and heat-pump designs is kind of disappointing. This isn't a fundamental thermodynamic issue; the Carnot efficiency for a gas burner at 2000 C running a refrigerator offering a 40 C temperature drop is close to the electric efficiency. In principle, it could be a more efficient way to use stored hydrogen than a fuel cell. In practice, it isn't. Maybe actually taking advantage of such high temperature differences requires very good refractory alloys. I would be curious to know the absolute efficiency proposed here rather than just a rough estimate of relative efficiency.

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